With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
fcFxPortNxPortRxDataFieldSize
fc Fx Port Nx Port Rx Data Field Size
1.3.6.1.2.1.75.1.2.3.1.4
The Receive Data Field Size of the attached NxPort. This object specifies the largest Data Field Size for an FT_1 frame that can be received by the NxPort.
Back to FIBRE-CHANNEL-FE-MIB MIB page.
IPHost Network monitor allows you to monitor fcFxPortNxPortRxDataFieldSize on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.